Electric Drive Apparatus and Electric Power Steering Apparatus

ABSTRACT

In an electric driving apparatus and an electric power steering apparatus, an electronic control assembly is divided into a power-supply circuit unit mounted on a metal substrate, a power-conversion circuit unit mounted on a metal substrate, and a control circuit unit mounted on a resin substrate. A power-supply-connector wiring part, which supplies electric power from the power-supply circuit unit to the power-conversion circuit unit and the control circuit unit, and a signal-transmission-connector wiring part, which transmits signals to be input to or output from the control circuit unit, are embedded in a synthetic-resin connector terminal assembly arranged on an outer peripheral side of each of the metal substrates. Connector terminals of the power-supply-connector wiring part and the signal-transmission-connector wiring part, which are exposed from the connector terminal assembly, are directly connected to corresponding connectors of the power-supply circuit unit, the power-conversion circuit unit, and the control circuit unit.

TECHNICAL FIELD

The present invention relates to an electric drive apparatus and anelectric power steering apparatus, and specifically to an electric driveapparatus and an electric power steering apparatus, both provided with abuilt-in electronic control unit.

BACKGROUND ART

In the general industrial machinery fields, a mechanical-system controlelement is driven by an electric motor. However, in recent years, therehave been proposed and developed various mechanically and electricallyintegrated electric drive apparatus, in which an electronic control unitthat is configured to control a rotational speed and a rotational torqueof an electric motor and comprised of a semiconductor device or thelike, is integrally incorporated in the electric motor.

For instance in an automotive electric power steering apparatusexemplified as a mechanically and electrically integrated electric driveapparatus, both of a rotational direction and a rotational torque of asteering shaft, which is rotated by operating a steering wheel by thedriver, are detected. The automotive electric power steering apparatusis configured to drive the electric motor so as to rotate the steeringshaft in the same direction as the rotational direction of the steeringshaft on the basis of the detected values, thereby generating a steeringassist torque. In order to control the electric motor, an electroniccontrol unit (ECU: Electronic Control Unit) is provided or incorporatedin the power steering apparatus.

As a prior-art electric power steering apparatus, Japanese patentprovisional publication No. JP2013-60119 A (Patent document 1) disclosessuch an electric power steering apparatus. Disclosed in the Patentdocument 1 is an electric power steering apparatus, which is constructedby an electric motor and an electronic control unit. The electric motoris housed in a motor housing having a cylindrical portion made ofaluminum alloy or the like, whereas the electronic control unit ishoused in an ECU housing, which is located on the opposite side to anoutput shaft in an axial direction of the motor housing. The electroniccontrol unit, which is housed in the ECU housing, is equipped with apower-supply circuit unit, a power-conversion circuit unit having apower switching element, such as a MOSFET, an IGBT or the like, fordriving and controlling the electric motor, and a control circuit unitfor controlling the power switching element. An output terminal of thepower switching element and an input terminal of the electric motor areelectrically connected to each other through a bus bar.

Electric power is supplied from a power source through a connectorterminal assembly made of synthetic resin to the electronic controlunit, which is housed in the

ECU housing. Also, detection signals from detection sensors,representing operating conditions and the like, are supplied to theelectronic control unit. The connector terminal assembly also functionsas a lid body. Hence, the connector terminal assembly is connected tothe electronic control unit in a manner so as to close an opening formedin the ECU housing. Also, the connector terminal assembly is fixedlyconnected to an outside surface of the ECU housing with fixing bolts.

As other electric drive apparatus, in which an electronic control unitis integrally incorporated, an electric brake, electric hydrauliccontrollers (regulators) for various hydraulic controls and the like arewell known.

CITATION LIST Patent Literature

Patent document 1: Japanese patent provisional publication No.2013-60119 (A)

SUMMARY OF INVENTION Technical Problem

By the way, the electric power steering apparatus disclosed in thePatent document 1 is located in the engine room of an automotivevehicle, and thus a small-size configuration is required. In particular,the recent trend is for a large number of accessories such as exhaustemission control apparatus, safety measure apparatus and the like to beinstalled in the engine room of the automotive vehicle. Hence, a varietyof accessories as well as the electric power steering apparatus have tobe reduced in size as much as possible. Additionally, it is required toreduce the number of component parts.

In the electric power steering apparatus having the configuration asdisclosed in the Patent document 1, the power-supply circuit unit, thepower-conversion circuit unit, and the control circuit unit are mountedon two substrates in total. On the other hand, the number of electricalcomponents needed to control the electric motor has roughly beendecided. Hence, when mounting the required number of electricalcomponents on these two substrates, as a matter of course, the radialsize of the ECU housing, in which the electronic control unit is housed,tends to be increased or enlarged. Structurally, in the electric powersteering apparatus, the limitation on its axial length is relativelysmaller, but there is a tendency for enlargement of its radial size tobe limited. Therefore, it would be desirable to reduce the size of theaforesaid housing in the radial direction.

To reduce the radial size, it is effective to utilize such aconfiguration that the power-supply circuit unit, the power-conversioncircuit unit, and the control circuit unit are divided into threeindividual sections. According to this three-divided configuration,electrical components needed to control the electric motor are alsodivided into three, and thus the area of each individual substrate canbe reduced as compared to a two-divided configuration, thereby reducingthe radial size.

However, for the purpose of supplying electric power, control signalsand the like to the three-divided individual substrates, thethree-divided configuration also requires a complicatedconnector-wiring-part configuration that uses a large number of relayconnectors. This leads to several problems such as increased number ofcomponent parts and difficulty in downsizing. Additionally, electricalcomponents, which construct the power-supply circuit unit and thepower-conversion circuit unit, generate a large amount of heat. Indownsizing, it is necessary to more efficiently radiate or dissipateheat generated from these electrical components to the outside.

It is, therefore, in view of the previously-described drawbacks of theprior art, an object of the invention to provide a new electric driveapparatus and a new electric power steering apparatus, configured tosuppress a housing, in which an electronic control unit is housed, frombeing enlarged in the radial direction, enable reduced number ofcomponents such as relay connectors and the like, and have a simplifiedheat-radiation structure.

Solution to Problem

In order to accomplish the aforementioned and other objects, theapparatus of the present invention is characterized in that anelectronic control assembly is divided into a power-supply circuit unithaving a main function that generates a power supply and mounted on ametal substrate, a power-conversion circuit unit having a main functionthat drives an electric motor and mounted on a metal substrate, and acontrol circuit unit having a main function that controls thepower-conversion circuit unit and mounted on a resin substrate, in thatat least a power-supply-connector wiring part that supplies electricpower from the power-supply circuit unit to the power-conversion circuitunit and the control circuit unit and a signal-transmission-connectorwiring part that transmits signals to be input to or output from thecontrol circuit unit are embedded in a synthetic-resin connectorterminal assembly arranged on an outer peripheral side of each of themetal substrates, and in that connector terminals of thepower-supply-connector wiring part and the signal-transmission-connectorwiring part, which are exposed from the connector terminal assembly, aredirectly connected to corresponding connectors of the power-supplycircuit unit, the power-conversion circuit unit, and the control circuitunit.

Advantageous Effects of Invention

According to the invention, electric components, which construct anelectronic control unit, are mounted on three substrates according torespective functions, and thus it is possible to reduce the radial sizeof each individual substrate. Additionally, connector wiring parts,through which individual circuit units are electrically connected toeach other, are arranged in a manner so as to be positioned on the outerperipheries of the metal substrates and directly connected to thecorresponding circuit units, and thus it is possible to reduce thenumber of components of a connector terminal assembly. As a result ofthis, the apparatus of the invention can provide an advantageous effectsuch as simplified configuration. Furthermore, the apparatus of theinvention can provide an advantageous effect that a sufficientheat-radiation cross-sectional area of the metal substrates themselvesor a heat-radiation substrate to which the metal substrates are fixed isensured.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a general perspective view illustrating a steering deviceillustrated as one example to which the present invention is applied.

FIG. 2 is a general perspective view illustrating an electric powersteering apparatus exemplified as a mechanically and electricallyintegrated electric drive apparatus.

FIG. 3 is a disassembled perspective view illustrating one embodiment ofthe electric power steering apparatus according to the presentinvention.

FIG. 4 is a perspective view of a power-supply circuit unit shown inFIG. 3.

FIG. 5 is a perspective view of a power-conversion circuit unit shown inFIG. 3.

FIG. 6 is a perspective view of a control circuit unit shown in FIG. 3.

FIG. 7 is a perspective view of a lid body equipped with connectorterminals shown in FIG. 3, as viewed at a low oblique angle.

FIG. 8 is a plan view illustrating the lid body viewed from thedirection of the plane A-A shown in FIG. 3.

FIG. 9 is a sectional view illustrating a cross section of the electricpower steering apparatus taken along the plane B-B of FIG. 8, but anelectric motor part is omitted.

FIG. 10 is a sectional view illustrating a cross section of the electricpower steering apparatus taken along the plane C-C of FIG. 8, but theelectric motor part is omitted.

FIG. 11 is a sectional view illustrating a cross section of the electricpower steering apparatus taken along the plane D-D of FIG. 8, but theelectric motor part is omitted.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are hereinafter described in detailwith reference to the accompanying drawings. It will be understood thatthe invention is not limited to the particular embodiments shown anddescribed hereunder, but that various changes and modifications may bemade without departing from the inventive concept of this invention.

Prior to explaining the embodiments of the invention, the configurationof a steering device illustrated as one example to which the inventionis applied, and the configuration of an electric power steeringapparatus exemplified as a mechanically and electrically integratedelectric drive apparatus are described briefly with reference to FIGS.1-2.

First of all, the steering device for steering front road wheels of anautomotive vehicle is explained. The steering device 1 is constructed asshown in FIG. 1. A pinion (not shown) is provided at the lower end of asteering shaft 2, which is linked to a steering wheel (not shown). Thepinion is kept in meshed-engagement with a rack (not shown) extending ina left-and-right direction of a vehicle body. Tie rods 3 are linked toboth ends of the rack, for steering the front road wheels in theleft-and-right direction. The rack is covered by a rack housing 4. Arubber boot 5 is provided between the rack housing and each tie rod 3.

Also provided is an electric power steering apparatus 6 for assistingsteering torque when the steering wheel is rotatably operated.Concretely, a torque sensor 7 is provided for detecting a rotationaldirection and a rotational torque of the steering shaft 2. Furtherprovided are an electric-motor part 8 for applying a steering assistforce based on the detected values of torque sensor 7 to the rack via agear 10, and an electronic control unit (ECU) part 9 for controlling anelectric motor located in the electric-motor part 8. The outerperipheral portion of the output-shaft side of electric-motor part 8 ofelectric power steering apparatus 6 is fixedly connected to the gear 10at three points with bolts (not shown). On the other hand, electroniccontrol unit part 9 is provided on the opposite side to the output shaftof electric-motor part 8.

As shown in FIG. 2, electric-motor part 8 is constructed by a motorhousing 11A having a cylindrical portion made of aluminum alloy or thelike, and the electric motor (not shown) housed in the motor housing. Onthe other hand, electronic control unit part 9 is constructed by an ECUhousing 11B located on the opposite side to the output shaft in an axialdirection of the motor housing 11A and made of aluminum alloy or thelike, and an electronic control assembly (not shown) housed in the ECUhousing.

Motor housing 11A and ECU housing 11B are integrally fixed together withfixing bolts at their opposed end faces. The electronic controlassembly, which is housed in the ECU housing 11B, is comprised of apower-supply circuit unit configured to generate a required powersupply, a power-conversion circuit unit having a power switching elementincluding a MOSFET (a metal oxide semiconductor FET), an IGBT (aninsulated gate bipolar transistor) or the like, for driving andcontrolling the electric motor of electric-motor part 8, and a controlcircuit unit for controlling the power switching element. An outputterminal of the power switching element and an input terminal of theelectric motor are electrically connected to each other through a busbar.

A lid body 12, which is made of synthetic resin and also serves as aconnector terminal assembly, is fixed on another end face of ECU housing11B with fixing bolts. Lid body 12 is equipped with a power-supplyconnector terminal formation part 12A, a detection-sensor connectorterminal formation part 12B, and a control-state-transmission connectorterminal formation part 12C for transmitting or sending out a controlstate to an external apparatus. Electric power is supplied from a powersource through the power-supply connector terminal formation part 12A oflid body 12 made of synthetic resin to the electronic control assemblyhoused in the ECU housing 11B. Also, detection signals from detectionsensors, representing operating conditions and the like, are suppliedthrough the detection-sensor connector terminal formation part 12B tothe electronic control assembly. Furthermore, a control-state signal,representing a current control state of the electric power steeringapparatus, is transmitted or sent out through thecontrol-state-transmission connector terminal formation part 12C to theelectronic control assembly.

Hereupon, lid body 12 is configured to cover the entire opening of ECUhousing 11B. In lieu thereof, the lid body equipped with downsizedconnector terminals may be inserted into an insertion through holeformed in the ECU housing 11B, for electric-connection with theelectronic control assembly.

In the electric power steering apparatus 6 configured as discussedabove, when steering shaft 2 is rotated in either rotational directionby operating the steering wheel, torque sensor 7 detects both arotational direction and a rotational torque of steering shaft 2. Thecontrol circuit unit calculates a driving manipulated variable fordriving the electric motor on the basis of the detected values. On thebasis of the calculated driving manipulated variable, the electric motoris driven by the power switching element of the power-conversion circuitunit. As a result, the output shaft of the electric motor is driven soas to rotate the steering shaft 2 in the same direction as therotational direction of the steering shaft. Rotary motion of the outputshaft is transmitted from the pinion (not shown) through the gear 10 tothe rack (not shown), and hence the automotive vehicle is steered.Detailed description of these configuration and operation of thesteering device will be omitted, because they are well known.

By the way, in the electric power steering apparatus as discussed above,a variety of accessories as well as the electric power steeringapparatus have to be reduced in size as much as possible, because therecent trend is for a large number of accessories such as exhaustemission control apparatus, safety measure apparatus and the like to beinstalled in the engine room of the automotive vehicle. Also, in theelectric power steering apparatus, the number of electrical componentsneeded to control the electric motor and constructing the power-supplycircuit unit, the power-conversion circuit unit, and the control circuitunit, has roughly been decided. Therefore, when mounting the requirednumber of electrical components on two substrates in total as disclosedin the Patent document 1, as a matter of course, the radial size of thehousing, in which the electronic control unit is housed, tends to beincreased or enlarged.

To reduce the radial size, it is effective to divide the power-supplycircuit unit, the power-conversion circuit unit, and the control circuitunit into three individual sections. According to this three-dividedconfiguration, electrical components needed to control the electricmotor are also divided into three, and thus the area of each individualsubstrate can be reduced as compared to a two-divided configuration,thereby reducing the radial size.

However, for the purpose of supplying electric power, control signalsand the like to the three-divided individual substrates, thethree-divided configuration also requires a complicatedconnector-wiring-part configuration that uses a large number of relayconnectors. This leads to several problems such as increased number ofcomponent parts and difficulty in downsizing. Additionally, electricalcomponents, which construct the power-supply circuit unit and thepower-conversion circuit unit, generate a large amount of heat. Indownsizing, it is necessary to more efficiently radiate or dissipateheat generated from these electrical components to the outside.

In view of the background as discussed above, in the shown embodiment,the electric power steering apparatus having the following configurationhas been proposed.

That is to say, the electric power steering apparatus of the embodimentis configured such that the electronic control assembly is divided intoa power-supply circuit unit having a main function that generates apower supply and mounted on a metal substrate, a power-conversioncircuit unit having a main function that drives an electric motor andmounted on a metal substrate, and a control circuit unit having a mainfunction that controls the power-conversion circuit unit and mounted ona resin substrate, and that at least a power-supply-connector wiringpart that supplies electric power from the power-supply circuit unit tothe power-conversion circuit unit and the control circuit unit and asignal-transmission-connector wiring part that transmits signals to beinput to or output from the control circuit unit are embedded in asynthetic-resin connector terminal assembly arranged on an outerperipheral side of each of the metal substrates, and that connectorterminals of the power-supply-connector wiring part and thesignal-transmission-connector wiring part, which are exposed from theconnector terminal assembly, are directly connected to correspondingconnectors of the power-supply circuit unit, the power-conversioncircuit unit, and the control circuit unit.

The configuration of one embodiment of the electric power steeringapparatus according to the invention is hereunder described withreference to the following drawings, but, the shape of the lid bodyshown in the following drawings is somewhat modified from that of lidbody 12 shown in FIG. 2. However, the lid body shown in the followingdrawings and the lid body 12 shown in FIG. 2 are identical in function.

Referring to FIG. 3, there is shown the disassembled perspective view ofelectric power steering apparatus 6. The electric motor is generallyhoused in the motor housing 11A. As discussed previously, motor housing11A and ECU housing 11B are made of aluminum alloy, and formedseparately from each other. In lieu thereof, these two housings may beintegrally formed as a same housing.

Electronic control unit part 9 is comprised of the ECU housing 11Bfixedly connected onto the opposite side to the output shaft (not shown)of the electric motor housed in the motor housing 11A, and the lid bodyfixedly connected to the ECU housing 11B with three fixing bolts 13. Asdescribed later, lid body 12 also serves as a connector terminalassembly. The lid body is made of synthetic resin by injection molding.By the way, various connector wiring parts (described later) aresimultaneously embedded in the lid body 12 by insert molding.

The electronic control assembly, which is comprised of the power-supplycircuit unit 14, the power-conversion circuit unit 15, and the controlcircuit unit 16 and the like, is housed in the housing space, defined bythe ECU housing 11B and the lid body 12. Metal substrates 17, 18, eachof which is made of a metal material such as aluminum, aluminum alloy orthe like, are located in the ECU housing 11B. Electrical components,which construct the power-supply circuit unit 14 and thepower-conversion circuit unit 15, are mounted on the respective metalsubstrates 17, 18 by single-sided mounting. As described later, thesemetal substrates 17, 18 also function as heat radiation members. Thus,these metal substrates are arranged in thermal-contact with the ECUhousing 11B so as to dissipate or radiate heat.

That is, metal substrates 17, 18 have a heat-radiation function thatdissipates or radiates heat from both the power-supply circuit unit 14and the power-conversion circuit unit 15 to the ECU housing 11B. Hence,the inner peripheral side of ECU housing 11B and the outer peripheralside of each of metal substrates 17, 18 are structured to be kept inthermal-contact with each other.

In lieu thereof, heat from metal substrates 17, 18 may be radiatedthrough fixing bolts (i.e., fixing bolts 44 shown in FIG. 9), by whichthese metal substrates are fixed to the lid body 12. In this case, aninsert nut is embedded in the lid body 12, and the insert nut has onlyto be kept in thermal-contact with the ECU housing 11B.

Hereupon, metal substrates 17, 18 are both formed thicker, for thepurpose of enhancing their radiating abilities. Also, to improve thethermal contact performance, a heat-radiation functional material havinga high thermal conductivity, such as a thermally conductive adhesive, aheat-radiation sheet, a heat-radiation grease, or the like, isinterleaved between the outer peripheral surface of each of metalsubstrates 17, 18 and the inner peripheral surface of ECU housing 11B.The reason for forming each of metal substrates 17, 18 thicker will behereinafter described in detail with reference to FIG. 9.

Power-supply circuit unit 14 having a main function that generates ahigh-voltage direct-current power supply used for an inverter device fordriving the electric motor and that generates a low-voltagedirect-current power supply used for a control circuit such as amicrocomputer or the like, is located inside of the lid body 12. Asshown in FIG. 4, mounted on one side of the metal substrate 17 made of ametal material having a high thermal conductivity such as aluminum orthe like, are electrical components such as condensers 19, a coil 20, aswitching element 21 including MOSFETs (metal oxide semiconductor FETs),a power-supply side connector 22 to which a power-supply side connectorterminal from a battery is connected, a high-voltage side connector 23to which a high-voltage side connector terminal for supplying ahigh-voltage power supply to the power-conversion circuit unit 15 isconnected, and a low-voltage side connector 24 to which a low-voltageside connector terminal for supplying a low-voltage power supply to thecontrol circuit unit 16 is connected. Metal substrate 17 is configuredby forming an insulating layer on an aluminum substrate and by printinga wiring pattern using a copper foil on the insulating layer. Electricalcomponents are mounted on the printed wiring pattern and electricallyconnected.

Regarding the power-supply circuit unit 14, electrical components, eachof which is comparatively large (tall) in shape (in size), such ascondensers 19, coil 20, connectors 22-24 and the like, are used. By theway, connectors 22, 23 are press-fit (snap-fit) type connectors, havingresiliencies that snap and bias respective connector terminals back tothe insides of connectors 22, 23. Thus, the mere insertion of theconnector terminal into the associated connector ensures easy connectionbetween them.

Power-conversion circuit unit 15, which has a main function that drivesthe electric motor and performs inverter control therefor, is located inthe ECU housing 11B. Regarding the power-conversion circuit unit 15, themetal substrate 18 of power-conversion circuit unit 15 is arranged to beopposed to the metal substrate 17 of power-supply circuit unit 14. Thatis, as can be seen from the drawings, the metal substrate 18 ofpower-conversion circuit unit 15 is arranged to be opposed to and keptin contact with the metal substrate 17 of power-supply circuit unit 14.

The two opposed faces (i.e., two contact surfaces) of the metalsubstrate 18 of power-conversion circuit unit 15 and the metal substrate17 of power-supply circuit unit 14 have a substantially same shape,thereby facilitating thermal conduction between them. Furthermore, aheat-radiation functional material having a high thermal conductivity,such as a thermally conductive adhesive, a heat-radiation sheet, aheat-radiation grease, or the like, is interleaved between them.

Regarding the power-conversion circuit unit 15, as shown in FIG. 5,mounted on the metal substrate 18 made of a metal material having a highthermal conductivity such as aluminum or the like, are a power switchingelement 25 including a plurality of MOSFETs (metal oxide semiconductorFETs) or an IGBT (an insulated gate bipolar transistor), outputconnectors 26U, 26V, 26W for outputs from the power switching element,and connector terminals 27A-27D and the like for signal inputs from agate, a drain, a source and for feeding an operating state of theswitching element 25 back to the control circuit unit 16. Also providedis an inverter-side connector 28 for receiving electric-power supplyfrom the power-supply circuit unit 14. In the shown embodiment, inaddition to six switching elements 25, three fail-safe switchingelements 25 are further provided.

By the way, output connectors 26U, 26V, 26W are press-fit (snap-fit)type connectors, having resiliencies that snap and bias respectiveconnector terminals of a bus bar connected to the electric motor back tothe insides of output connectors 26U, 26V, 26W. Thus, the mere insertionof the bus-bar connector terminal into the associated output connectorensures easy connection between them.

Metal substrate 18 is configured by forming an insulating layer on analuminum substrate and by printing a wiring pattern using a copper foilon the insulating layer. Electrical components are mounted on theprinted wiring pattern and electrically connected. For goodunderstanding, in FIG. 5, the metal substrate is reversed in a manner soas to highlight the side on which the aforementioned electricalcomponents are mounted. Actually, as shown in FIG. 3, the electricalcomponents are mounted on the underside of the metal substrate.

Control circuit unit 16, which has a main function of executingswitching control for the switching element 25 of power-conversioncircuit unit 15, is located between the power-conversion circuit unit 15and the motor housing 11A. ECU housing 11B is formed with fourresin-substrate mounting bosses 29 extending toward the motor housing11A. The resin substrate of control circuit unit 16 is fixed onto theresin-substrate mounting bosses 29 with mounting bolts 30.

Regarding the control circuit unit 16, as shown in FIG. 6, amicrocomputer 32, which controls the switching element 25, is mounted ona resin substrate 31 made of synthetic resin. Also, other electricalcomponents such as peripheral circuits of microcomputer 32 are mountedon the resin substrate 31, but these other electrical components areomitted in FIG. 6.

The resin substrate 31 is arranged to be spaced apart from thepower-conversion circuit unit 15 by a predetermined distance. Electricalcomponents that construct the power-conversion circuit unit 15 arelocated in the space defined by the predetermined distance. Controlcircuit unit 16 and power-conversion circuit unit 15 are connected toeach other by connector terminals 27A-27D.

Each of connector terminals 27A-27D has a length longer than thepredetermined distance between the resin substrate 31 and thepower-conversion circuit unit 15. Connector terminal 27A is connected toa connection hole 33A of resin substrate 31, connector terminal 27B isconnected to a connection hole 33B, connector terminal 27C is connectedto a connection hole 33C, and connector terminal 27D is connected to aconnection hole 33D. Also connected with a connection hole 33E, which isformed in the control substrate (resin substrate 31), is a control-sideconnector terminal for signal-transmission and for low-voltage powersupply. The control-side connector terminal is embedded in an insulatingregion part (described later) of the lid body 12.

In this manner, the power-supply circuit unit 14, the power-conversioncircuit unit 15, and the control circuit unit 16 are arranged from thelid body 12 toward the motor housing 11A in that order. As discussedabove, the control circuit unit 16 is arranged in a manner so as to bespaced apart from the power-supply circuit unit 14, and hence it ispossible to supply a stable electric power after having eliminated powersource noise to the control circuit unit 16.

Returning to FIG. 3, the lid body 12, in which the connector wiring parthas been embedded, is configured to cover the opening of ECU housing11B. In a similar manner to the lid body shown in FIG. 2, lid body 12 ofFIG. 3 is equipped on its outside surface in the axial direction with apower-supply connector terminal formation part 12A, a detection-sensorconnector terminal formation part 12B, and a control-state-transmissionconnector terminal formation part 12C for transmitting or sending out acontrol state to an external apparatus. In lieu thereof, the connectorterminal formation part 12B and the connector terminal formation part12C may be integrally formed as a single connector terminal formationpart. Electric power is supplied from a power source (not shown) throughthese connector terminal formation parts 12A-12C to the power-supplycircuit unit 14. Also, signals from detection sensors are inputted tothe control circuit unit 16.

Referring to FIG. 7, there is shown the concrete configuration of lidbody 12. In FIG. 7, lid body 12, which also serves as the connectorterminal assembly, is equipped inside thereof with various connectorwiring parts and their connector terminals.

First, a power-source-connector wiring part serving as apower-supply-connector wiring part, through which the connector terminalformation part 12A connected to an external power source (i.e., anon-vehicle battery) and the power-supply circuit unit 14 are connectedwith each other, is embedded in the lid body 12, such that apower-source side connector terminal 34, located at the top end of thepower-supply-connector wiring part, is exposed from the lid body 12. Thepower-source side connector terminal 34 is positioned inside of the sideperipheral surface of lid body (by the way, the side peripheral surfacecorresponding to a surface forming a sealed region (described later)together with the ECU housing). The power-source side connector terminal34 is connected to the power-supply side connector 22 of power-supplycircuit unit 14. As discussed previously, the mere insertion of thepower-source side connector terminal 34 into the press-fit typepower-supply side connector 22 ensures or completes easy connectionbetween them. The power-source-connector wiring part is clearly shown inFIG. 11.

Secondly, a high-voltage side connector wiring part serving as apower-supply-connector wiring part, through which the power-supplycircuit unit 14 and the power-conversion circuit unit 15 are connectedwith each other, is embedded in the lid body 12. Both ends of thehigh-voltage side connector wiring part are formed as a high-voltageside connector terminal 35 and an inverter-side connector terminal 36,such that these connector terminals are exposed from the lid body 12.One connector terminal, that is, the high-voltage side connectorterminal 35 is connected to the high-voltage side connector 23 ofpower-supply circuit unit 14, while the other connector terminal, thatis, the inverter-side connector terminal 36 is connected to theinverter-side connector 28 of power-conversion circuit unit 15. Thehigh-voltage side connector wiring part is clearly shown in FIG. 10.

The high-voltage side connector terminal 35 is connected to thehigh-voltage side connector 23 of power-supply circuit unit 14. Asdiscussed previously, the mere insertion of the high-voltage sideconnector terminal 35 into the press-fit type high-voltage sideconnector 23 completes easy connection between them. Also, theinverter-side connector terminal 36 is connected to the inverter-sideconnector 28 of power-conversion circuit unit 15. TIG welding (tungsteninert-gas arc welding) the inverter-side connector terminal 36 and theinverter-side connector 28 together completes easy connection betweenthem.

The cross-section of the high-voltage side connector wiring part betweenthe high-voltage side connector terminal 35 and the inverter-sideconnector terminal 36 is formed into a C shape in which a connectorwiring portion corresponding to the inverter-side connector terminal 36is relatively longer than that of the high-voltage side connectorterminal. The relatively longer connector wiring portion is embedded inthe synthetic resin that forms the lid body 12, so as to form or providea high-voltage side insulating region part 45. As clearly shown in FIG.10, the high-voltage side insulating region part 45 is configured toextend through an insertion part formed on an end face of the outerperipheral side of each of metal substrates 17, 18 to thepower-conversion circuit unit 15. The insertion part may be formed as acut-out cut on the outer peripheral side of each of metal substrates 17,18. In lieu thereof, the insertion part may be formed as an insertionthrough hole. Furthermore, the high-voltage side insulting region part45, which constructs the high-voltage side connector wiring part, islocated between the outer peripheral side of each of metal substrates17, 18 and the inside of the side peripheral surface of the connectorlid body 12. The detailed arrangement of the high-voltage side insultingregion part will be described later with reference to FIG. 10.

Thirdly, a low-voltage side connector wiring part serving as apower-supply-connector wiring part, through which the power-supplycircuit unit 14 and the control circuit unit 16 are connected with eachother, is embedded in the lid body 12. Both ends of the low-voltage sideconnector wiring part are formed as a low-voltage side connectorterminal 37 and a control-side connector terminal 38, such that theseconnector terminals are exposed from the lid body 12. One connectorterminal, that is, the low-voltage side connector terminal 37 isconnected to the low-voltage side connector 24 of power-supply circuitunit 14, while the other connector terminal, that is, the control-sideconnector terminal 38 is connected to the connection hole 33E of controlcircuit unit 16.

Also, a signal-transmission-connector wiring part, which is locatedadjacent to the low-voltage side connector wiring part and connected toboth the detection-sensor connector terminal formation part 12B and thecontrol-state-transmission connector terminal formation part 12C fortransmitting signals, is embedded in the lid body 12, such that acontrol-side connector terminal 39 is exposed from the lid body 12. Thelow-voltage side connector wiring part is clearly shown in FIG. 11.

The low-voltage side connector terminal 37 is connected to thelow-voltage side connector 24 of power-supply circuit unit 14. The mereengagement of the low-voltage side connector terminal 37 with the sockettype low-voltage side connector 24 completes easy connection betweenthem. Also, the control-side connector terminal 38 and thesignal-transmission control-side connector terminal 39 are connected tothe connection hole 33E of control circuit unit 16. Soldering thecontrol-side connector terminals 38, 39 and the connection hole 33Etogether completes easy connection between them.

The above-mentioned low-voltage side connector wiring part and thesignal-transmission connector wiring part are both embedded in thesynthetic resin that forms the lid body 12, so as to form or provide alow-voltage side insulating region part 46. As clearly shown in FIG. 11,the low-voltage side insulating region part 46 is configured to extendthrough an insertion part formed on an end face of the outer peripheralside of each of metal substrates 17, 18 to the control circuit unit 16.The insertion part may be formed as a cut-out cut on the outerperipheral side of each of metal substrates 17, 18. In lieu thereof, theinsertion part may be formed as an insertion through hole. Furthermore,the low-voltage side insulting region part 46, which constructs thelow-voltage side connector wiring part, is located between the outerperipheral side of each of metal substrates 17, 18 and the inside of theside peripheral surface of the connector lid body 12. The detailedarrangement of the low-voltage side insulting region part will bedescribed later with reference to FIG. 11.

As can be appreciated from FIG. 7, lid body 12 is formed on its innerperipheral surface with metal-substrate mounting bosses 43 for fixingthe metal substrate 17 of power-supply circuit unit 14 and the metalsubstrate 18 of power-conversion circuit unit 15 together. Furthermore,the power-source side connector terminal 34, the high-voltage sideconnector terminal 35, the inverter-side connector terminal 36, thelow-voltage side connector terminal 37, the control-side connectorterminal 38, and the signal-transmission control-side connector terminal39 are arranged close to the inner peripheral surface of lid body 12.

That is, the power-source side connector terminal 34, the high-voltageside connector terminal 35, the inverter-side connector terminal 36, thelow-voltage side connector terminal 37, the control-side connectorterminal 38, and the signal-transmission control-side connector terminal39 are arranged in a manner so as to be positioned near the respectiveouter peripheral sides of the substrates of power-supply circuit unit14, power-conversion circuit unit 15, and control circuit unit 16.

Hereby, electrical components, which construct the power-supply circuitunit 14, the power-conversion circuit unit 15, and the control circuitunit 16, can be arranged near the center of each of the substrates.Hence, it is possible to reduce the size in the radial direction.

Assuming that some of the above-mentioned terminals pass through insideof the respective substrates, insertion parts therefor have to be formedin the respective metal substrates 17, 18. This means thatheat-radiation passage cross-sectional areas of metal substrates 17, 18become narrow. Thus, there is a possibility of deteriorated heatdissipation.

In contrast, in the shown embodiment, the connector wiring partscontaining the respective connector terminals are arranged in a mannerso as to be positioned outside of the metal substrates 17, 18. Thiseliminates the necessity of forming useless insertion parts inside ofthe metal substrates 17, 18, thereby ensuring a sufficientheat-radiation passage cross-sectional area.

In the lid body 12 of the embodiment, the connector wiring part forsupplying electric power from the power-supply circuit unit 14 to boththe power-conversion circuit unit 15 and the control circuit unit 16,and the connector wiring part for transmitting signals to be input to oroutput from the control circuit unit are embedded in the connectorterminal assembly made of synthetic resin by insert molding.Additionally, connector terminals of the power-supply-connector wiringpart and the signal-transmission-connector wiring part, which areexposed from the connector terminal assembly, are directly connected tocorresponding connectors of the power-supply circuit unit, thepower-conversion circuit unit, and the control circuit unit.

For the reasons discussed above, wirings between the power-conversioncircuit unit 15 and the control circuit unit 16 can be eliminated, andhence the respective connector wiring parts can be directly connected tocorresponding connectors without using any extra relay connectorcomponents. Accordingly, extra relay connector components areunnecessary, and thus reduced number of components contributes todownsizing. Furthermore, the simplified connector-wiring-partconfiguration suppresses an increase in assembly man-hour, andconsequently suppresses a rise in unit price of product.

Also, in the shown embodiment, the connector wiring parts containing therespective connector terminals are arranged in a manner so as to bepositioned outside of the resin substrate 31 as well as the metalsubstrates 17, 18. This eliminates the necessity of forming uselessinsertion parts inside of the metal substrates 17, 18, thereby ensuringa sufficient heat-radiation passage cross-sectional area.

The assembling order of the electric power steering apparatus shown inFIG. 3 is as follows. First, the metal substrate 17 of power-supplycircuit unit 14 and the metal substrate 18 of power-conversion circuitunit 15 are opposed to each other, and then fixing bolts 44 areinserted. After this, the fixing bolts 44 are screwed into therespective metal-substrate mounting bosses 43 formed in the lid body 12,for fastening the power-supply circuit unit 14, the power-conversioncircuit unit 15, and the lid body 12, together with the fixing bolts.

In this state, connection between the power-supply side connector 22 ofpower-supply circuit unit 14 and the power-source side connectorterminal 34 is completed, while connection between the high-voltage sideconnector 23 of the high-voltage side connector wiring part and thehigh-voltage side connector terminal 35 is completed. Furthermore,connection between the low-voltage side connector 24 and the low-voltageside connector terminal 37 is completed.

Next, in the above-mentioned state, the high-voltage side insultingregion part 45 has protruded from the power-conversion circuit unit 15,and hence the inverter-side connector terminal 36, which is exposed fromthe insulting region part, and the inverter-side connector 28 areconnected together by the use of a TIG-welding torch.

Subsequently to the above, ECU housing 11B is inserted toward the lidbody 12, and then the ECU housing and the lid body are fixedly fastenedtogether with the fixing bolts 13. After this, the fixing bolts 30 arescrewed into the respective resin-substrate mounting bosses 29 forfastening and mounting the control circuit unit 16 on theresin-substrate mounting bosses. In this manner, the control circuitunit 16 and the ECU housing 11B are united together.

Under the above-mentioned state, the connection holes 33A-33E, which areformed in the resin substrate 31 of control circuit unit 16, and thecorresponding connector terminals 27A-27D and connector terminals 38, 39are connected together by soldering. In this manner, electronic controlunit part 9 can be completed.

Thereafter, electronic control unit part 9 is fixedly connected onto themotor housing 11A with fixing bolts, utilizing a mounting flange formedintegral with the ECU housing 11B. In this manner, the motor housing 11Aand the ECU housing 11B are united together.

Details of the configuration of the electronic control assembly, whichis housed in the ECU housing 11B, are hereunder described with referenceto FIGS. 8-11.

Referring to FIG. 8, there is shown the plan view illustrating the lidbody 12 viewed from the direction of the plane A-A shown in FIG. 3, andalso illustrating the planar structure of the power-conversion circuitunit 15. However, the detailed configuration/structure ofpower-conversion circuit unit 15 itself has already been explained withreference to FIG. 5. Thus, the detailed description of thepower-conversion circuit unit will be omitted because the abovedescription thereon seems to be self-explanatory. An important pointrelated to the electronic control assembly is that insertion parts 40A,48 are formed on respective end faces of the outer peripheral side ofmetal substrate 18.

The insertion part 40A is a linear cut-out cut in the outer periphery ofmetal substrate 18. The previously-discussed low-voltage side insultingregion part 46 is configured to extend through the insertion part 40A tothe control circuit unit 16. The reason for the insertion part 40Aformed as a linear “cut-out” is that there are a large number of wiringparts passing through the low-voltage side insulting region part 46, andthus the increased “cut-out” area permits these wiring parts to beinserted through the low-voltage side insulting region part 46. As amatter of course, as shown in FIG. 11, an insertion part 40B is alsoformed in the outer periphery of metal substrate 17 in a manner so as tobe substantially conformable to the insertion part 40A formed in themetal substrate 18.

In a similar manner to the above, the insertion part 48 is a cut-out cutin the outer periphery of metal substrate 18. The previously-discussedhigh-voltage side insulting region part 45 is configured to extendthrough the insertion part 48 to the power-conversion circuit unit 15.As a matter of course, an insertion part is also formed in the outerperiphery of metal substrate 17 in a manner so as to be substantiallyconformable to the insertion part 48 formed in the metal substrate 18.

The cross section of the electric power steering apparatus taken alongthe plane B-B of FIG. 8 is hereunder described with reference to FIG. 9,but the electric motor part is omitted in FIG. 9.

In FIG. 9, the ECU housing 11B and the motor housing 11A are fixedlyconnected to each other with a plurality of fixing bolts 41 screwed intothe mounting flanges formed integral with the respective housings. In asimilar manner, the ECU housing 11B and the lid body 12 are fixedlyconnected to each other with the plurality of fixing bolts 13 screwedinto the mounting flanges formed integral with the ECU housing and thelid body, respectively.

Part of the lid body 12 except the connector terminal formation parts12A-12C is housed in the opening of the ECU housing 11B. The outerperipheral surface of the lid body 12 is kept in close-contact with theinner peripheral surface of ECU housing 11B. Seal rings 42 are locatedin the outer peripheral surface of lid body 12. Undesirable entry ofwater or the like into the clearance between the lid body 12 and the ECUhousing 11B can be prevented by means of the seal rings 42.

Lid body 12 is formed on its inner periphery with metal-substratemounting bosses 43 for fixing the metal substrate 17 of power-supplycircuit unit 14 and the metal substrate 18 of power-conversion circuitunit 15 together. Such metal-substrate mounting bosses 43 are generallyformed at four points, but, as seen in FIG. 3, in the embodiment onlyone place is omitted and thus the metal-substrate mounting bosses 43 areformed at only three points. The reason for this is to reduce the areaof metal substrate 18 of power-conversion circuit unit 15 as much aspossible and to reduce the number of fixing bolts.

Each of the metal substrate 17 of power-supply circuit unit 14 and themetal substrate 18 of power-conversion circuit unit 15 is formed withinsertion holes through which fixing bolts 44 are inserted. With thesimplified structure, the metal substrate 17 of power-supply circuitunit 14 and the metal substrate 18 of power-conversion circuit unit 15are strongly fixed onto the metal-substrate mounting bosses 43 byscrewing the fixing bolts 44 from the side of metal substrate 18 ofpower-conversion circuit unit 15 into the respective metal-substratemounting bosses 43. Furthermore, the metal substrate 17 of power-supplycircuit unit 14 and the metal substrate 18 of power-conversion circuitunit 15 are arranged to be opposed to each other, thereby enabling heattransfer between them.

As previously described with reference to FIG. 3, metal substrates 17,18 have a heat-radiation function that emits or radiates heat from boththe power-supply circuit unit 14 and the power-conversion circuit unit15 to the ECU housing 11B. Hence, the inner peripheral side of ECUhousing 11B and the outer peripheral side of each of metal substrates17, 18 are structured to be kept in thermal-contact with each other.Additionally, to improve the thermal contact performance, aheat-radiation functional material having a high thermal conductivity,such as a thermally conductive adhesive, a heat-radiation sheet, aheat-radiation grease, or the like, is interleaved between the outerperipheral surface of each of metal substrates 17, 18 and the innerperipheral surface of ECU housing 11B.

Hereupon, in the shown embodiment metal substrates 17, 18 are bothformed thicker, for the purpose of enhancing their radiating abilities.Usually, a thin metal substrate made of aluminum alloy is used as metalsubstrates 17, 18. However, in the case of the use of such a thin metalsubstrate, a heat-radiation passage cross-sectional area is insufficientand thus a phenomenon that heat is accumulated in the thin metalsubstrate tends to occur. Thus, there is a possibility for theaccumulated heat to exert a bad influence upon the electrical componentsof power-supply circuit unit 14 and power-conversion circuit unit 15.

One way of improving the heat-dissipation performance of thepreviously-noted thin metal substrate is to fix the thin metal substrateonto a heat-radiation substrate prepared separately. However, this leadsto the task of increasing manufacturing costs owing to theheat-radiation substrate die-formed by die-casting and also leads to thetask of increasing the number of fixing bolts used for fixing the metalsubstrate onto the heat-radiation substrate (with the proviso that theapparatus of the invention can be applied to a structure in which aheat-radiation substrate together with the metal substrate has been usedor prepared separately).

In contrast to the above, in the shown embodiment, the thickness ofmetal substrate 17 and the thickness of metal substrate 18 are formedthicker. Also, these metal substrates are thermally connected to eachother via a heat-radiation functional material interleaved between them.As a result of this, metal substrate 17 and metal substrate 18 can betreated or used just like a single thick heat-radiation substrate.Therefore, by virtue of both of metal substrate 17 and metal substrate18, a sufficient heat-radiation passage can be ensured, thereby enablingsufficient heat dissipation from the electrical components ofpower-supply circuit unit 14 and power-conversion circuit unit 15.

In the shown embodiment, each of the metal substrates is structured tohave a two times or more thickness than a conventional thin metalsubstrate. Generally, the thickness of a conventional thin metalsubstrate is approximately 2 millimeters. In the shown embodiment, thethickness of each of the metal substrates is set to be a thicknessranging from 4 millimeters to 10 millimeters. By the way, heat of eachof metal substrates 17, 18 is transferred to the ECU housing 11B, andthen released from the outer peripheral surface of ECU housing 11B tothe atmosphere.

By fastening the metal substrate 17 of power-supply circuit unit 14 andthe metal substrate 18 of power-conversion circuit unit 15 together withfixing bolts 44, the heat-radiation passage of power-supply circuit unit14 and power-conversion circuit unit 15 can be enlarged as if a unitedheat-radiation substrate has been provided or used. Furthermore, thenumber of fixing bolts can be reduced, thus enabling reduced unit priceof product.

As previously stated, the use of a heat-radiation substrate requires adie-formed heat-radiation substrate formed by die-casting, increases thenumber of fixing bolts for fixedly connecting each of the metalsubstrates and the heat-radiation substrate, and further increases thenumber of component parts owing to a heat-radiation functional materialsuch as a heat-radiation grease or the like, needed on both faces of theheat-radiation substrate.

In contrast, the apparatus of the embodiment merely requires that eachof metal substrates 17, 18 should be formed thicker. This eliminates thenecessity of manufacturing a die-formed heat-radiation substrate bydie-casting. Thus it is possible to keep down the unit price of product.Also, this means reduced number of fixing bolts needed for fixing metalsubstrates 17, 18 onto respective heat-radiation substrates and reducedinstallation places of heat-radiation functional materials. As a result,it is possible to reduce the number of component parts and reducedassembly man-hour, thus suppressing a rise in total unit price ofproduct.

Electrical components, such as condensers, a coil and the like, whichconstruct the power-supply circuit unit 14 and have a large shapedimension, are housed between the metal substrate 17 of power-supplycircuit unit 14 and the bottom face of the inside of lid body 12. Theseelectrical components, each of which has a large shape dimension,require a large housing space. Therefore, the apparatus of theembodiment utilizes a long sealed region defined between the outerperipheral surface of lid body 12 and the inner peripheral surface ofECU housing 11B, so as to form the above-mentioned large housing space.

That is to say, the electric power steering apparatus is located in theengine room of an automotive vehicle, and thus a situation where theelectric power steering apparatus is wetted with rainwater duringdriving in rainy weather or water in the puddle during driving on theroad containing puddles, often occurs. For this reason, a sufficientwater-tightness in the contact region of the ECU housing 11B and the lidbody 12 has to be ensured. Hence, the sealed region between both the ECUhousing and the lid body is lengthened and additionally two seal rings42 are installed in the sealed region.

In this manner, seal rings 42 are installed double, and thus a morereliable water-tightness can be ensured. Additionally, by virtue of thelong sealed region, a large housing space can be formed between the lidbody 12 and the metal substrate of power-supply circuit unit 14. Thepower-supply circuit unit 14, which is constructed by electricalcomponents, each having a large shape dimension, can be easily housed inthe large housing space. As discussed above, by virtue of an effectiveutilization of the space defined for ensuring a more reliablewater-tightness, the power-supply circuit unit 14, which is constructedby electrical components, each having a large shape dimension, can beeffectively housed.

Hereby, it is possible to shorten the axial length as much as possible.Also, the power-source side connector terminal 34, which is connected tothe power source, and the press-fit (snap-fit) type power-supply sideconnector 22 of power-supply circuit unit 14 are arranged to be opposedto each other, and configured such that the power-source side connectorterminal is directly inserted into and connected to the press-fit typepower-supply side connector. This facilitates the assembly work.

The cross section of the electric power steering apparatus taken alongthe plane C-C of FIG. 8 is hereunder described with reference to FIG.10, but the electric motor part is omitted in FIG. 10.

In FIG. 10, the high-voltage side insulating region part 45 made ofsynthetic resin extends from the bottom face of the inside of lid body12 toward the control circuit unit 16. The high-voltage side insulatingregion part 45 is configured to extend through the insertion part 47provided on the outer peripheral side of metal substrate 17 and theinsertion part 48 provided on the outer peripheral side of metalsubstrate 18 to the power-conversion circuit unit 15. By the way, theinsertion part 47 of metal substrate 17 and the insertion part 48 ofmetal substrate 18 are formed between the outer peripheral surfaces ofmetal substrates 17, 18 and the side peripheral surface of lid body 12.

A high-voltage side connector wiring part 49 is embedded in thehigh-voltage side insulating region part 45. One end of the high-voltageside connector wiring part 49 is formed as the high-voltage sideconnector terminal 35, whereas the other end of the high-voltage sideconnector wiring part 49 is formed as the inverter-side connectorterminal 36. In this manner, the provision of high-voltage sideinsulating region part 45 ensures electrical insulation between thehigh-voltage side connector wiring part 49 and each of metal substrate17, 18.

The high-voltage side connector wiring part 49 including thehigh-voltage side connector terminal 35 and the inverter-side connectorterminal 36 is formed into a C shape. The high-voltage side connector 23of power-supply circuit unit 14 and the inverter-side connector 28 ofpower-conversion circuit unit 15 are arranged reversely from each other,and thus these connecting pairs can be reciprocally connected.

Therefore, when fixing the lid body 12 onto the ECU housing 11B,connection between the high-voltage side connector terminal 35 and thepress-fit type high-voltage side connector 23 can be completed byinserting the high-voltage side connector terminal into the press-fittype high-voltage side connector. Also, connection between theinverter-side connector terminal 36 and the inverter-side connector 28can be completed by TIG-welding the inverter-side connector terminal tothe inverter-side connector. At this time, the control circuit unit 16is not yet installed, and hence the TIG-welding torch can be easilybrought close to the inverter-side connector terminal 36 as well as theinverter-side connector 28.

The high-voltage side insulating region part 45, which constructs thehigh-voltage side connector wiring part, is arranged in a manner so asto be positioned outside of the metal substrates 17, 18 and the resinsubstrate 31. Hence, there are not any useless insertion parts formedinside of the metal substrates 17, 18, thereby ensuring a sufficientheat-radiation passage cross-sectional area.

The cross section of the electric power steering apparatus taken alongthe plane D-D of FIG. 8 is hereunder described with reference to FIG.11, but the electric motor part is omitted in FIG. 11.

In FIG. 11, a power-supply-connector wiring part 50, which connects theexternal power source and the power-supply circuit unit 14, is embeddedin the connector terminal formation part 12A. The power-source sideconnector terminal 34, located at the top end of thepower-supply-connector wiring part 50, is exposed from the lid body 12.The power-source side connector terminal 34 is connected to thepower-supply side connector 22 of power-supply circuit unit 14. The mereinsertion of the power-source side connector terminal 34 into thepress-fit type power-supply side connector 22 ensures or completes easyconnection between them.

Also, the low-voltage side insulating region part 46 made of syntheticresin extends from the bottom face of the inside of lid body 12 towardthe control circuit unit 16. The low-voltage side insulating region part46 is configured to extend through the insertion part 40B formed in themetal substrate 17 and the insertion part 40A formed in the metalsubstrate 18 to the control circuit unit 16. By the way, the insertionpart 40B of metal substrate 17 and the insertion part 40A of metalsubstrate 18 are formed between the outer peripheral surfaces of metalsubstrates 17, 18 and the side peripheral surface of lid body 12.

A low-voltage side connector wiring part 51 is embedded in thelow-voltage side insulating region part 46. One end of the low-voltageside connector wiring part 51 is formed as the low-voltage sideconnector terminal 37, whereas the other end of the low-voltage sideconnector wiring part 51 is formed as the control-side connectorterminal 38. In this manner, the provision of low-voltage sideinsulating region part 46 ensures electrical insulation between thelow-voltage side connector wiring part 51 and each of metal substrate17, 18.

The low-voltage side connector wiring part 51 including the low-voltageside connector terminal 37 and the control-side connector terminal 38 isformed into a C shape. The low-voltage side connector 24 of power-supplycircuit unit 14 and the connection hole 33E of control circuit unit 16can be reciprocally connected. Therefore, when fixing the lid body 12,connection between the low-voltage side connector terminal 37 and thepress-fit type low-voltage side connector 24 can be completed byinserting the low-voltage side connector terminal into the press-fittype low-voltage side connector. Also, connection between thecontrol-side connector terminal 38 and the connection hole 33E of theresin substrate 31 of control circuit unit 16 can be completed bysoldering them together, while inserting the control-side connectorterminal into the connection hole.

At this time, the resin substrate 31 of control circuit unit 16 hasalready been fixed onto the resin-substrate mounting bosses 29 withfixing bolts 30. Under this state, the control-side connector terminal38 and the connection hole 33E can be connected together by soldering.

Lid body 12 is provided with the detection-sensor external connectorterminal formation part 12B, and the control-state-transmission externalconnector terminal formation part 12C. Furthermore, thesignal-transmission-connector wiring part (not shown), which transmitssignals supplied through these connector terminal formation parts 12B,12C, is embedded in the lid body 12, and then the signal-transmissioncontrol-side connector terminal 39 is exposed from the lid body 12. Thesignal-transmission-connector wiring part together with the low-voltageside connector wiring part 51 is embedded in the insulating region part46. The signal-transmission-connector wiring part is connected to theconnection hole 33E of control circuit unit 16.

In the shown embodiment, the low-voltage side insulting region part 46,which constructs the low-voltage side connector wiring part, is arrangedin a manner so as to be positioned outside of the metal substrates 17,18 and the resin substrate 31. Hence, there are not any uselessinsertion parts formed inside of the metal substrates 17, 18, therebyensuring a sufficient heat-radiation passage cross-sectional area.

Moreover, as can be appreciated from the respective drawings, in theshown embodiment, the resin substrate 31 of control circuit unit 16, themetal substrate 18 of power-conversion circuit unit 15, and the metalsubstrate 17 of power-supply circuit unit 14 are arranged in that order,when viewed from the motor housing 11A. Hence, heat from the electricmotor is shut off by means of the resin substrate 31 having aheat-insulating property higher than the metal substrates 17, 18,thereby reducing heat received by the electronic control unit part fromthe electric motor.

As discussed above, in the shown embodiment, the electronic controlassembly is divided into a power-supply circuit unit 14 having a mainfunction that generates a power supply and mounted on a metal substrate17, a power-conversion circuit unit 15 having a main function thatdrives an electric motor and mounted on a metal substrate 18, and acontrol circuit unit 16 having a main function that controls thepower-conversion circuit unit and mounted on a resin substrate 31, andthus it is possible to reduce the number of electrical componentsmounted on each individual substrate. As a result of this, it ispossible to reduce the radial size of each individual substrate.

By the way, owing to the three-divided substrate configuration, theaxial length tends to lengthen, but, such a somewhat lengthened axiallength is permitted structurally in the electric power steeringapparatus. From the viewpoint of a whole product, it is advantageous toreduce the radial size/constitution rather than the lengthened axiallength.

The connector wiring part that supplies electric power from thepower-supply circuit unit 14 to the power-conversion circuit unit 15 andthe control circuit unit 16 and the connector wiring part that transmitssignals to be input to or output from the control circuit unit areembedded in the connector terminal assembly made of synthetic resin byinsert molding. Additionally, connector terminals of the connectorwiring parts, which are exposed from the connector terminal assembly,that is, the connector wiring part for supplying a high-voltage powersupply, the connector wiring part for supplying a low-voltage powersupply, and the signal-transmission-connector wiring part, are directlyconnected to corresponding connectors of the power-supply circuit unit,the power-conversion circuit unit, and the control circuit unit.

For the reasons discussed above, wirings between the power-conversioncircuit unit 15 and the control circuit unit 16 can be eliminated, andhence the respective connector wiring parts can be directly connected tocorresponding connectors without using any extra relay connectorcomponents. Accordingly, extra relay connector components areunnecessary, and thus reduced number of components contributes todownsizing. Furthermore, the simplified connector-wiring-partconfiguration suppresses an increase in assembly man-hour, andconsequently suppresses a rise in unit price of product.

Additionally, in the shown embodiment, the thickness of metal substrate17 and the thickness of metal substrate 18 are formed thicker. Also,these metal substrates are thermally connected to each other via aheat-radiation functional material interleaved between them. As a resultof this, metal substrate 17 and metal substrate 18 can be treated orused just like a single thick heat-radiation substrate. Therefore, byvirtue of both of metal substrate 17 and metal substrate 18, asufficient heat-radiation passage can be ensured, thereby enablingsufficient heat dissipation from the electrical components ofpower-supply circuit unit 14 and power-conversion circuit unit 15.

By fastening the metal substrate 17 of power-supply circuit unit 14 andthe metal substrate 18 of power-conversion circuit unit 15 together withfixing bolts 44, the heat-radiation passage of power-supply circuit unit14 and power-conversion circuit unit 15 can be enlarged as if a unitedheat-radiation substrate has been provided or used. Furthermore, thenumber of fixing bolts can be reduced, thus enabling reduced unit priceof product. Moreover, the apparatus of the embodiment merely requiresthat each of metal substrates 17, 18 should be formed thicker. Thiseliminates the necessity of manufacturing a die-formed heat-radiationsubstrate by die-casting. Thus it is possible to keep down the unitprice of product.

Additionally, the power-supply circuit unit 14 that uses electricalcomponents, each of which has a large shape dimension, is housed in thehousing space between the metal substrate 17 and the lid body 12, inwhich a comparatively long sealed region exists. Hence, by virtue of aneffective utilization of the housing space, it is possible to shortenthe axial length as much as possible.

Furthermore, the power-source side connector terminal 34, thehigh-voltage side connector terminal 35, the inverter-side connectorterminal 36, the low-voltage side connector terminal 37, thecontrol-side connector terminal 38, and the signal-transmissioncontrol-side connector terminal 39 are arranged in a manner so as to bepositioned near the respective outer peripheral sides of the substratesof power-supply circuit unit 14, power-conversion circuit unit 15, andcontrol circuit unit 16. Hereby, electrical components, which constructthe power-supply circuit unit 14, the power-conversion circuit unit 15,and the control circuit unit 16, can be arranged near the center of eachof the substrates. Hence, it is possible to reduce the size in theradial direction. The respective connector terminals are arranged in amanner so as to be positioned outside of the metal substrates 17, 18.This eliminates the necessity of forming useless insertion parts insideof the metal substrates 17, 18, thereby ensuring a sufficientheat-radiation passage.

In the embodiment as discussed previously, the thickness of metalsubstrate 17 of power-supply circuit unit 14 and the thickness of metalsubstrate 18 of power-conversion circuit unit 15 are formed thicker. Themetal substrates 17, 18, which are stacked on another, serve as a unitedheat-radiation substrate. In lieu thereof, a conventional thin metalsubstrate may be used as a heat-radiation substrate. In this case,concretely, in order to dissipate or radiate heat generated fromelectrical components, which construct the power-supply circuit unit andthe power-conversion circuit unit, an aluminum alloy material having athickness greater than or equal to a predetermined dimension has to beprepared as a heat-radiation substrate, and then the heat-radiationsubstrate is located inside of the ECU housing and positioned to extendin the radial direction. Furthermore, the metal substrate of thepower-supply circuit unit and the metal substrate of thepower-conversion circuit unit are connected to both faces of theheat-radiation substrate, respectively, and the heat-radiation substrateis connected to the ECU housing so as to dissipate or radiate heat.

That is, an aluminum alloy material having the summed thickness of thethickness of metal substrate 17 and the thickness of metal substrate 18(with the proviso that a somewhat deviation of the thickness dimensioncan be tolerated) is used as a heat-radiation substrate, and then a thinmetal substrate of a conventional thickness is connected to thisheat-radiation substrate of the summed thickness for the purpose of heatradiation/dissipation. In this case, it is necessary to thermallyconnect the heat-radiation substrate to the ECU housing 11B.Furthermore, in the same manner as the embodiment, a heat-radiationfunctional material may be added for the purpose of promoting heatradiation/dissipation.

As discussed above, according to the invention, an electronic controlassembly is divided into a power-supply circuit unit having a mainfunction that generates a power supply and mounted on a metal substrate,a power-conversion circuit unit having a main function that drives anelectric motor and mounted on a metal substrate, and a control circuitunit having a main function that controls the power-conversion circuitunit and mounted on a resin substrate. Additionally, at least apower-supply-connector wiring part that supplies electric power from thepower-supply circuit unit to the power-conversion circuit unit and thecontrol circuit unit and a signal-transmission-connector wiring partthat transmits signals to be input to or output from the control circuitunit are embedded in a synthetic-resin connector terminal assemblyarranged on an outer peripheral side of each of the metal substrates.Furthermore, connector terminals of the power-supply-connector wiringpart and the signal-transmission-connector wiring part, which areexposed from the connector terminal assembly, are directly connected tocorresponding connectors of the power-supply circuit unit, thepower-conversion circuit unit, and the control circuit unit.

According to the above, electric components, which construct anelectronic control unit, are mounted on three substrates according torespective functions, and thus it is possible to reduce the radial sizeof each individual substrate. Additionally, connector wiring parts,through which individual circuit units are electrically connected toeach other, are arranged in a manner so as to be positioned on the outerperipheries of the metal substrates and directly connected to thecorresponding circuit units, and thus it is possible to reduce thenumber of components of the connector terminal assembly. As a result ofthis, the apparatus of the invention can provide an advantageous effectsuch as simplified configuration. Furthermore, the apparatus of theinvention can provide an advantageous effect that a sufficientheat-radiation cross-sectional area of the metal substrates themselvesor a heat-radiation substrate to which the metal substrates are fixed isensured.

While the foregoing is a description of the preferred embodimentscarried out the invention, it will be understood that the invention isnot limited to the particular embodiments shown and described herein,but that various changes and modifications may be made without departingfrom the scope or spirit of this invention. For instance, for betterunderstanding, the aforementioned embodiments are explained in detail,but all components/elements as explained above do not need to beprovided. Furthermore, a part of components/elements of one embodimentmay be replaced with a part of another embodiment. Moreover, acomponent/element of one embodiment may be added to components/elementsof another embodiment. Also, regarding each of components/elements ofeach embodiment, addition, deletion, or replacement may be arbitrarilymade.

As an electric drive apparatus and an electric power steering apparatusbased on the embodiments shown and explained above, several aspectsdescribed below can be taken into account.

That is to say, according to one aspect of the electric drive apparatus,there is provided an electric drive apparatus constructed by an electricmotor for driving a mechanical-system control element and an electroniccontrol unit located opposite to an output shaft of the electric motorand configured to control the electric motor, the electronic controlunit being equipped with an ECU housing connected to a motor housing inwhich the electric motor is housed and an electronic control assemblyhoused in the ECU housing for driving and controlling the electricmotor, characterized in that the electronic control assembly is dividedinto a power-supply circuit unit having a main function that generates apower supply and mounted on a metal substrate, a power-conversioncircuit unit having a main function that drives the electric motor andmounted on a metal substrate, and a control circuit unit having a mainfunction that controls the power-conversion circuit unit and mounted ona resin substrate, in that at least a power-supply-connector wiring partthat supplies electric power from the power-supply circuit unit to thepower-conversion circuit unit and the control circuit unit and asignal-transmission-connector wiring part that transmits signals to beinput to or output from the control circuit unit are embedded in asynthetic-resin connector terminal assembly arranged on an outerperipheral side of each of the metal substrates, and in that connectorterminals of the power-supply-connector wiring part and thesignal-transmission-connector wiring part, which are exposed from theconnector terminal assembly, are directly connected to correspondingconnectors of the power-supply circuit unit, the power-conversioncircuit unit, and the control circuit unit.

According to a preferable aspect of the electric drive apparatus, theconnector terminal assembly serves as a lid body that closes an openingof the ECU housing in which the power-supply circuit unit, thepower-conversion circuit unit, and the control circuit unit are housed.

According to another preferable aspect, the power-supply circuit unit,the power-conversion circuit unit, and the control circuit unit arearranged from the lid body in that order, electrical components of thepower-supply circuit unit and the power-conversion circuit unit aremounted on a first side of each of the metal substrates by single-sidedmounting, and a second side of the metal substrate of the power-supplycircuit unit and a second side of the metal substrate of thepower-conversion circuit unit are fixed to be opposed to each other andthermally connected to each other, the second side being opposite to thefirst side of each of the metal substrates.

According to a further preferable aspect, the power-supply-connectorwiring part is configured to extend through an insertion part formed onan outer peripheral side of each of the metal substrates of thepower-supply circuit unit and the power-conversion circuit unit to thepower-conversion circuit unit, and the signal-transmission-connectorwiring part is configured to extend through an insertion part formed onthe outer peripheral side of each of the metal substrates of thepower-supply circuit unit and the power-conversion circuit unit to thecontrol circuit unit.

According to a still further preferable aspect, thepower-supply-connector wiring part comprises a high-voltage sideconnector wiring part and a low-voltage side connector wiring part, thehigh-voltage side connector wiring part is connected through a firstinsertion part formed on the outer peripheral side of each of the metalsubstrates of the power-supply circuit unit and the power-conversioncircuit unit to the power-conversion circuit unit, and the low-voltageside connector wiring part is connected through a second insertion partformed on the outer peripheral side of each of the metal substrates ofthe power-supply circuit unit and the power-conversion circuit unit tothe control circuit unit.

According to another preferable aspect, a portion of the high-voltageside connector wiring part other than terminals of both ends of thehigh-voltage side connector wiring part is embedded in the syntheticresin that forms the lid body so as to form a high-voltage sideinsulating region part, the high-voltage side insulating region part ispositioned in the respective first insertion parts of the metalsubstrates, a portion of the low-voltage side connector wiring partother than terminals of both ends of the low-voltage side connectorwiring part and a portion of the signal-transmission-connector wiringpart other than terminals of both ends of thesignal-transmission-connector wiring part are embedded in the syntheticresin that forms the lid body so as to form a low-voltage sideinsulating region part, and the low-voltage side insulating region partis positioned in the respective second insertion parts of the metalsubstrates.

According to another preferable aspect, the high-voltage side connectorwiring part, the low-voltage side connector wiring part, and thesignal-transmission-connector wiring part are arranged on the outerperipheral side of each of the metal substrate of the power-supplycircuit unit and the metal substrate of the power-conversion circuitunit.

From another viewpoint of the electric power steering apparatus, thereis provided an electric power steering apparatus constructed by anelectric motor for applying a steering assist force to a steering shaftand an electronic control unit located opposite to an output shaft ofthe electric motor and configured to control the electric motor, theelectronic control unit being equipped with an ECU housing connected toa motor housing in which the electric motor is housed and an electroniccontrol assembly housed in the ECU housing for driving and controllingthe electric motor, characterized in that the electronic controlassembly is divided into a power-supply circuit unit having a mainfunction that generates a power supply and mounted on a metal substrate,a power-conversion circuit unit having a main function that drives theelectric motor and mounted on a metal substrate, and a control circuitunit having a main function that controls the power-conversion circuitunit and mounted on a resin substrate, in that at least apower-supply-connector wiring part that supplies electric power from thepower-supply circuit unit to the power-conversion circuit unit and thecontrol circuit unit and a signal-transmission-connector wiring partthat transmits signals to be input to or output from the control circuitunit are embedded in a synthetic-resin connector terminal assemblyarranged on an outer peripheral side of each of the metal substrates,and in that connector terminals of the power-supply-connector wiringpart and the signal-transmission-connector wiring part, which areexposed from the connector terminal assembly, are directly connected tocorresponding connectors of the power-supply circuit unit, thepower-conversion circuit unit, and the control circuit unit.

According to a preferable aspect of the electric power steeringapparatus, the connector terminal assembly serves as a lid body thatcloses an opening of the ECU housing in which the power-supply circuitunit, the power-conversion circuit unit, and the control circuit unitare housed.

According to another preferable aspect, the power-supply circuit unit,the power-conversion circuit unit, and the control circuit unit arearranged from the lid body in that order, electrical components of thepower-supply circuit unit and the power-conversion circuit unit aremounted on a first side of each of the metal substrates by single-sidedmounting, and a second side of the metal substrate of the power-supplycircuit unit and a second side of the metal substrate of thepower-conversion circuit unit are fixed to be opposed to each other andthermally connected to each other, the second side being opposite to thefirst side of each of the metal substrates.

According to a further preferable aspect, the power-supply-connectorwiring part is configured to extend through an insertion part formed onan outer peripheral side of each of the metal substrates of thepower-supply circuit unit and the power-conversion circuit unit to thepower-conversion circuit unit, and the signal-transmission-connectorwiring part is configured to extend through an insertion part formed onthe outer peripheral side of each of the metal substrates of thepower-supply circuit unit and the power-conversion circuit unit to thecontrol circuit unit.

According to a still further preferable aspect, thepower-supply-connector wiring part comprises a high-voltage sideconnector wiring part and a low-voltage side connector wiring part, thehigh-voltage side connector wiring part is connected through a firstinsertion part formed on the outer peripheral side of each of the metalsubstrates of the power-supply circuit unit and the power-conversioncircuit unit to the power-conversion circuit unit, and the low-voltageside connector wiring part is connected through a second insertion partformed on the outer peripheral side of each of the metal substrates ofthe power-supply circuit unit and the power-conversion circuit unit tothe control circuit unit.

According to another preferable aspect, a portion of the high-voltageside connector wiring part other than terminals of both ends of thehigh-voltage side connector wiring part is embedded in the syntheticresin that forms the lid body so as to form a high-voltage sideinsulating region part, the high-voltage side insulating region part ispositioned in the respective first insertion parts of the metalsubstrates, a portion of the low-voltage side connector wiring partother than terminals of both ends of the low-voltage side connectorwiring part and a portion of the signal-transmission-connector wiringpart other than terminals of both ends of thesignal-transmission-connector wiring part are embedded in the syntheticresin that forms the lid body so as to form a low-voltage sideinsulating region part, and the low-voltage side insulating region partis positioned in the respective second insertion parts of the metalsubstrates.

According to another preferable aspect, the high-voltage side connectorwiring part, the low-voltage side connector wiring part, and thesignal-transmission-connector wiring part are arranged on the outerperipheral side of each of the metal substrate of the power-supplycircuit unit and the metal substrate of the power-conversion circuitunit.

1. An electric drive apparatus constructed by an electric motor fordriving a mechanical-system control element and an electronic controlunit located opposite to an output shaft of the electric motor andconfigured to control the electric motor, the electronic control unitbeing equipped with an ECU housing connected to a motor housing in whichthe electric motor is housed and an electronic control assembly housedin the ECU housing for driving and controlling the electric motor,characterized in that the electronic control assembly is divided into apower-supply circuit unit having a main function that generates a powersupply and mounted on a metal substrate, a power-conversion circuit unithaving a main function that drives the electric motor and mounted on ametal substrate, and a control circuit unit having a main function thatcontrols the power-conversion circuit unit and mounted on a resinsubstrate, in that at least a power-supply-connector wiring part thatsupplies electric power from the power-supply circuit unit to thepower-conversion circuit unit and the control circuit unit and asignal-transmission-connector wiring part that transmits signals to beinput to or output from the control circuit unit are embedded in asynthetic-resin connector terminal assembly arranged on an outerperipheral side of each of the metal substrates, and that connectorterminals of the power-supply-connector wiring part and thesignal-transmission-connector wiring part, which are exposed from theconnector terminal assembly, are directly connected to correspondingconnectors of the power-supply circuit unit, the power-conversioncircuit unit, and the control circuit unit.
 2. The electric driveapparatus as recited in claim 1, wherein: the connector terminalassembly serves as a lid body that closes an opening of the ECU housingin which the power-supply circuit unit, the power-conversion circuitunit, and the control circuit unit are housed.
 3. The electric driveapparatus as recited in claim 2, wherein: the power-supply circuit unit,the power-conversion circuit unit, and the control circuit unit arearranged from the lid body in that order, and electrical components ofthe power-supply circuit unit and the power-conversion circuit unit aremounted on a first side of each of the metal substrates by single-sidedmounting, and a second side of the metal substrate of the power-supplycircuit unit and a second side of the metal substrate of thepower-conversion circuit unit are fixed to be opposed to each other andthermally connected to each other, the second side being opposite to thefirst side of each of the metal substrates.
 4. The electric driveapparatus as recited in claim 3, wherein: the power-supply-connectorwiring part is configured to extend through an insertion part formed onan outer peripheral side of the metal substrates of the power-supplycircuit unit and the power-conversion circuit unit to thepower-conversion circuit unit, and the signal-transmission-connectorwiring part is configured to extend through an insertion part formed onthe outer peripheral side of each of the metal substrates of thepower-supply circuit unit and the power-conversion circuit unit to thecontrol circuit unit.
 5. The electric drive apparatus as recited inclaim 4, wherein: the power-supply-connector wiring part comprises ahigh-voltage side connector wiring part and a low-voltage side connectorwiring part, the high-voltage side connector wiring part is connectedthrough a first insertion part formed on the outer peripheral side ofeach of the metal substrates of the power-supply circuit unit and thepower-conversion circuit unit to the power-conversion circuit unit, andthe low-voltage side connector wiring part is connected through a secondinsertion part formed on the outer peripheral side of each of the metalsubstrates of the power-supply circuit unit and the power-conversioncircuit unit to the control circuit unit.
 6. The electric driveapparatus as recited in claim 5, wherein: a portion of the high-voltageside connector wiring part other than terminals of both ends of thehigh-voltage side connector wiring part is embedded in the syntheticresin that forms the lid body so as to form a high-voltage sideinsulating region part, the high-voltage side insulating region part ispositioned in the respective first insertion parts of the metalsubstrates, a portion of the low-voltage side connector wiring partother than terminals of both ends of the low-voltage side connectorwiring part and a portion of the signal-transmission-connector wiringpart other than terminals of both ends of thesignal-transmission-connector wiring part are embedded in the syntheticresin that forms the lid body so as to form a low-voltage sideinsulating region part, and the low-voltage side insulating region partis positioned in the respective second insertion parts of the metalsubstrates.
 7. The electric drive apparatus as recited in claim 6,wherein: the high-voltage side connector wiring part, the low-voltageside connector wiring part, and the signal-transmission-connector wiringpart are arranged on the outer peripheral side of each of the metalsubstrate of the power-supply circuit unit and the metal substrate ofthe power-conversion circuit unit.
 8. An electric power steeringapparatus constructed by an electric motor for applying a steeringassist force to a steering shaft and an electronic control unit locatedopposite to an output shaft of the electric motor and configured tocontrol the electric motor, the electronic control unit being equippedwith an ECU housing connected to a motor housing in which the electricmotor is housed and an electronic control assembly housed in the ECUhousing for driving and controlling the electric motor, characterized inthat the electronic control assembly is divided into a power-supplycircuit unit having a main function that generates a power supply andmounted on a metal substrate, a power-conversion circuit unit having amain function that drives the electric motor and mounted on a metalsubstrate, and a control circuit unit having a main function thatcontrols the power-conversion circuit unit and mounted on a resinsubstrate, in that at least a power-supply-connector wiring part thatsupplies electric power from the power-supply circuit unit to thepower-conversion circuit unit and the control circuit unit and asignal-transmission-connector wiring part that transmits signals to beinput to or output from the control circuit unit are embedded in asynthetic-resin connector terminal assembly arranged on an outerperipheral side of each of the metal substrates, and that connectorterminals of the power-supply-connector wiring part and thesignal-transmission-connector wiring part, which are exposed from theconnector terminal assembly, are directly connected to correspondingconnectors of the power-supply circuit unit, the power-conversioncircuit unit, and the control circuit unit.
 9. The electric powersteering apparatus as recited in claim 8, wherein: the connectorterminal assembly serves as a lid body that closes an opening of the ECUhousing in which the power-supply circuit unit, the power-conversioncircuit unit, and the control circuit unit are housed.
 10. The electricpower steering apparatus as recited in claim 9, wherein: thepower-supply circuit unit, the power-conversion circuit unit, and thecontrol circuit unit are arranged from the lid body in that order, andelectrical components of the power-supply circuit unit and thepower-conversion circuit unit are mounted on a first side of each of themetal substrates by single-sided mounting, and a second side of themetal substrate of the power-supply circuit unit and a second side ofthe metal substrate of the power-conversion circuit unit are fixed to beopposed to each other and thermally connected to each other, the secondside being opposite to the first side of each of the metal substrates.11. The electric power steering apparatus as recited in claim 10,wherein: the power-supply-connector wiring part is configured to extendthrough an insertion part formed on an outer peripheral side of themetal substrate s of the power-supply circuit unit and thepower-conversion circuit unit to the power-conversion circuit unit, andthe signal-transmission-connector wiring part is configured to extendthrough an insertion part formed on the outer peripheral side of each ofthe metal substrates of the power-supply circuit unit and thepower-conversion circuit unit to the control circuit unit.
 12. Theelectric power steering apparatus as recited in claim 11, wherein: thepower-supply-connector wiring part comprises a high-voltage sideconnector wiring part and a low-voltage side connector wiring part, thehigh-voltage side connector wiring part is connected through a firstinsertion part formed on the outer peripheral side of each of the metalsubstrates of the power-supply circuit unit and the power-conversioncircuit unit to the power-conversion circuit unit, and the low-voltageside connector wiring part is connected through a second insertion partformed on the outer peripheral side of each of the metal substrates ofthe power-supply circuit unit and the power-conversion circuit unit tothe control circuit unit.
 13. The electric power steering apparatus asrecited in claim 12, wherein: a portion of the high-voltage sideconnector wiring part other than terminals of both ends of thehigh-voltage side connector wiring part is embedded in the syntheticresin that forms the lid body so as to form a high-voltage sideinsulating region part, the high-voltage side insulating region part ispositioned in the respective first insertion parts of the metalsubstrates, a portion of the low-voltage side connector wiring partother than terminals of both ends of the low-voltage side connectorwiring part and a portion of the signal-transmission-connector wiringpart other than terminals of both ends of thesignal-transmission-connector wiring part are embedded in the syntheticresin that forms the lid body so as to form a low-voltage sideinsulating region part, and the low-voltage side insulating region partis positioned in the respective second insertion parts of the metalsubstrates.
 14. The electric power steering apparatus as recited inclaim 13, wherein: the high-voltage side connector wiring part, thelow-voltage side connector wiring part, and thesignal-transmission-connector wiring part are arranged on the outerperipheral side of each of the metal substrate of the power-supplycircuit unit and the metal substrate of the power-conversion circuitunit.